.\" $OpenBSD: EVP_PKEY_new.3,v 1.20 2024/08/24 09:15:36 tb Exp $
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.Dd $Mdocdate: August 24 2024 $
.Dt EVP_PKEY_NEW 3
.Os
.Sh NAME
.Nm EVP_PKEY_new ,
.Nm EVP_PKEY_up_ref ,
.Nm EVP_PKEY_free ,
.Nm EVP_PKEY_new_raw_private_key ,
.Nm EVP_PKEY_new_raw_public_key ,
.Nm EVP_PKEY_new_CMAC_key ,
.Nm EVP_PKEY_new_mac_key ,
.Nm EVP_PKEY_get_raw_private_key ,
.Nm EVP_PKEY_get_raw_public_key
.Nd public and private key allocation and raw key handling functions
.Sh SYNOPSIS
.In openssl/evp.h
.Ft EVP_PKEY *
.Fn EVP_PKEY_new void
.Ft int
.Fo EVP_PKEY_up_ref
.Fa "EVP_PKEY *pkey"
.Fc
.Ft void
.Fo EVP_PKEY_free
.Fa "EVP_PKEY *pkey"
.Fc
.Ft EVP_PKEY *
.Fo EVP_PKEY_new_raw_private_key
.Fa "int type"
.Fa "ENGINE *engine"
.Fa "const unsigned char *rawpriv"
.Fa "size_t rawlen"
.Fc
.Ft EVP_PKEY *
.Fo EVP_PKEY_new_raw_public_key
.Fa "int type"
.Fa "ENGINE *engine"
.Fa "const unsigned char *rawpub"
.Fa "size_t rawlen"
.Fc
.Ft EVP_PKEY *
.Fo EVP_PKEY_new_CMAC_key
.Fa "ENGINE *engine"
.Fa "const unsigned char *rawpriv"
.Fa "size_t rawlen"
.Fa "const EVP_CIPHER *cipher"
.Fc
.Ft EVP_PKEY *
.Fo EVP_PKEY_new_mac_key
.Fa "int type"
.Fa "ENGINE *engine"
.Fa "const unsigned char *rawpriv"
.Fa "int rawlen"
.Fc
.Ft int
.Fo EVP_PKEY_get_raw_private_key
.Fa "const EVP_PKEY *pkey"
.Fa "unsigned char *rawpriv"
.Fa "size_t *rawlen"
.Fc
.Ft int
.Fo EVP_PKEY_get_raw_public_key
.Fa "const EVP_PKEY *pkey"
.Fa "unsigned char *rawpub"
.Fa "size_t *rawlen"
.Fc
.Sh DESCRIPTION
The
.Vt EVP_PKEY
structure is used by various OpenSSL functions which require a general
private or public key without reference to any particular algorithm.
.Pp
The
.Fn EVP_PKEY_new
function allocates an empty
.Vt EVP_PKEY
structure.
The reference count is set to 1.
To add a private or public key to it, use the functions described in
.Xr EVP_PKEY_set1_RSA 3 .
.Pp
.Fn EVP_PKEY_up_ref
increments the reference count of
.Fa pkey
by 1.
.Pp
.Fn EVP_PKEY_free
decrements the reference count of
.Fa pkey
by 1, and if the reference count reaches zero, frees it up.
If
.Fa pkey
is a
.Dv NULL
pointer, no action occurs.
.Pp
.Fn EVP_PKEY_new_raw_private_key
allocates a new
.Vt EVP_PKEY .
The NID of a public key algorithm that supports raw private keys, i.e.\&
.Dv EVP_PKEY_HMAC ,
.Dv EVP_PKEY_X25519 ,
or
.Dv EVP_PKEY_ED25519 ,
is provided in the
.Fa type
argument and
.Fa rawlen
bytes of raw private key data of that type in
.Fa rawpriv .
The public key data is automatically derived from the given private
key data, if appropriate for the algorithm type.
The
.Fa ENGINE *engine
argument is always ignored and passing
.Dv NULL
is recommended.
.Pp
.Fn EVP_PKEY_new_raw_public_key
works in the same way as
.Fn EVP_PKEY_new_raw_private_key
except that
.Fa rawpub
points to the raw public key data.
The
.Vt EVP_PKEY
structure is initialised without any private key information.
Algorithm types that support raw public keys are
.Dv EVP_PKEY_X25519
and
.Dv EVP_PKEY_ED25519 .
.Pp
.Fn EVP_PKEY_new_CMAC_key
works in the same way as
.Fn EVP_PKEY_new_raw_private_key
except that it only handles the
.Dv EVP_PKEY_CMAC
algorithm type.
The additional
.Fa cipher
argument specifies the cipher algorithm
to be used during the creation of the CMAC.
It should be a standard encryption only cipher.
For example, AEAD and XTS ciphers should not be used.
.Pp
.Fn EVP_PKEY_new_mac_key
is a deprecated function that works in the same way as
.Fn EVP_PKEY_new_raw_private_key .
.Pp
.Fn EVP_PKEY_get_raw_private_key
writes up to
.Pf * Fa rawlen
bytes of raw private key data to the buffer starting at
.Fa rawpriv
and stores the number of bytes written in
.Pf * Fa rawlen .
The calling application is responsible for ensuring that the buffer
is large enough to receive the private key data.
If the
.Fa rawpriv
argument is
.Dv NULL ,
the number of bytes required to hold the key is stored in
.Pf * Fa rawlen .
This function only works for algorithms that support raw private keys.
Currently these are
.Dv EVP_PKEY_HMAC ,
.Dv EVP_PKEY_X25519 ,
and
.Dv EVP_PKEY_ED25519 .
.Pp
.Fn EVP_PKEY_get_raw_public_key
is similar to
.Fn EVP_PKEY_get_raw_private_key
except that it writes raw public key data.
This function only works for algorithms that support raw public keys.
Currently these are
.Dv EVP_PKEY_X25519
and
.Dv EVP_PKEY_ED25519 .
.Sh RETURN VALUES
.Fn EVP_PKEY_new ,
.Fn EVP_PKEY_new_raw_private_key ,
.Fn EVP_PKEY_new_raw_public_key ,
.Fn EVP_PKEY_new_CMAC_key ,
and
.Fn EVP_PKEY_new_mac_key
return either the newly allocated
.Vt EVP_PKEY
structure or
.Dv NULL
if an error occurred.
.Pp
.Fn EVP_PKEY_up_ref ,
.Fn EVP_PKEY_get_raw_private_key ,
and
.Fn EVP_PKEY_get_raw_public_key
return 1 for success or 0 for failure.
.Sh SEE ALSO
.Xr CMAC_Init 3 ,
.Xr d2i_PrivateKey 3 ,
.Xr evp 3 ,
.Xr EVP_PKCS82PKEY 3 ,
.Xr EVP_PKEY_asn1_new 3 ,
.Xr EVP_PKEY_check 3 ,
.Xr EVP_PKEY_cmp 3 ,
.Xr EVP_PKEY_CTX_new 3 ,
.Xr EVP_PKEY_get_default_digest_nid 3 ,
.Xr EVP_PKEY_meth_new 3 ,
.Xr EVP_PKEY_print_private 3 ,
.Xr EVP_PKEY_set1_RSA 3 ,
.Xr EVP_PKEY_size 3 ,
.Xr X509_get_pubkey_parameters 3
.Sh HISTORY
.Fn EVP_PKEY_new
and
.Fn EVP_PKEY_free
first appeared in SSLeay 0.6.0 and have been available since
.Ox 2.4 .
.Pp
.Fn EVP_PKEY_new_CMAC_key
first appeared in OpenSSL 1.1.1 and has been available since
.Ox 6.9 .
.Pp
.Fn EVP_PKEY_new_mac_key
first appeared in OpenSSL 1.0.0 and has been available since
.Ox 4.9 .
.Pp
.Fn EVP_PKEY_up_ref
first appeared in OpenSSL 1.1.0 and has been available since
.Ox 6.3 .
.Pp
.Fn EVP_PKEY_new_raw_private_key ,
.Fn EVP_PKEY_new_raw_public_key ,
.Fn EVP_PKEY_get_raw_private_key ,
and
.Fn EVP_PKEY_get_raw_public_key
first appeared in OpenSSL 1.1.1 and have been available since
.Ox 7.3 .
